1. Field of the Invention
The present invention relates to an air conditioner with a refrigerating cycle employing a non-azeotropic coolant mixture composed of high and low boiling coolants, and particularly, to an air conditioner efficiently operating the refrigerating cycle by effectively controlling a temperature gradient due to phase changes characteristic to the non-azeotropic coolant mixture.
2. Description of the Prior Art
FIGS. 1 and 2 are Mollier charts showing refrigerating cycles of air conditioners employing a heat pump that carries out both heating and cooling operations. The refrigerating cycle of FIG. 1 employs a single coolant and the refrigerating cycle of FIG. 2 employs an azeotropic coolant mixture.
The coolant is condensed by an outdoor heat exchanger when carrying out the cooling operation and is evaporated by the same when carrying out the heating operation. When the coolant is condensed or evaporated, the phase of the coolant changes.
When the phase of the single coolant of FIG. 1 changes, the pressure and temperature thereof are unchanged as indicated with a dotted line T showing an equal temperature.
When the phase of the non-azeotropic coolant mixture of FIG. 2 changes, the temperature thereof changes as indicated with dotted lines T1 and T2 showing equal temperatures (T1&lt;T2), respectively. Namely, the non-azeotropic coolant mixture demonstrates a temperature gradient when the composition of the non-azeotropic coolant mixture changes according to the phase change. The temperature gradient is dependent on the composition and mixing ratio of the non- azeotropic coolant mixture. The temperature gradient during an air-conditioning operation is, for example, about five degrees of centigrade between the inlet and outlet of the outdoor heat exchanger.
Conventional air conditioners employing the non-azeotropic coolant mixture, however, do not effectively utilize such a temperature gradient.